EUCHNER CETx-AR-xxx-AH-xxx (Unicode) - Manual (Page 7)

Operating Instructions Safety Switch CET.-AR-...-AH-...
7
The system is designed so that failures will not result in the loss of the safety func-
tion. The occurrence of failures is detected by cyclic self-monitoring at the latest
on the next demand to close the safety contacts (e.g. on starting).
Function of the guard locking
Version CET1-AR, guard locking by spring force
The lift tappet is pressed into the locked position by the force of the spring for the
guard locking pin in the actuator and unlocked electromagnetically by the safety
switch. The guard locking functions in accordance with the closed-circuit current
principle. The locked safety guard cannot be opened immediately in the event of
interruption of the power supply to the solenoid.
The guard locking pin of the actuator cannot be moved out of the recess and the
door is locked in the closed position as long as the lift tappet is pressed down by
the actuator.
When the operating voltage is present at the locking solenoid, the lift tappet is
extended and lifts the actuator's guard locking pin above the edge of the recess.
The safety door can then be opened.
Version CET2-AR, guard locking by solenoid force
Important:
The safety guard can be opened immediately in the event of interruption of the
solenoid power supply! Usage only in special cases in accordance with strict
evaluation of the accident risk (see DIN EN 1088 (1995), section 5.5)!
Example: If the risk of accidental locking inside a safety guard during a power
failure is higher than the risk of ineffective guard locking.
The lift tappet is held in locked position by electromagnetic force and released
by spring force. The guard locking operates in accordance with the open-circuit
current principle.
The safety door can be opened as long as the lift tappet is held in the extended
position.
The lift tappet is released when operating voltage is present at the guard locking
solenoid. The actuator's guard locking pin can now press the lift tappet down.
The safety door is locked as soon as the guard locking pin is fully inserted into
the recess.
Version CET3-AR, guard locking by spring force with door monitor-
ing output
Function as for CET1-AR, however here the door position is also monitored. The
door monitoring output OUT D is switched on as soon as the actuator protrudes
beyond the extended lift tappet (state: door closed, guard locking not active). The
output OUT D also remains switched on when guard locking is active.